Bay seniors ready to get over their nostalgia for iceberg lettuce might consider stopping by the Ferry Building this Saturday March 22. Demonstrations of cooking with nettles, fava leaves, orach and arugula will introduce you to the chewy new world of leafy greens. Even learn to make your own veggie rice paper rolls. The event is sponsored by CUESA (the Center for Urban Education about Sustainable Agriculture) and runs from 10 to 2. You can find it under the white tents.Free.